Hi everyone... the problem is with an LG4 '87...

I was getting an occasional SES after startup when it went out of closed loop, so I checked the codes and I was getting a code 15 - on Saturday I replaced the CTS and reset the codes, and now I'm getting the SES almost consistantly (more than before), and still, the only code it's throwing is 15.

I checked the voltage at the connector, and I'm getting 5v just like I should be, so I'm thinking that maybe the new CTS is defective maybe? Any other ideas? I did not splice in the new connector that came with the CTS as the one on the car looked clean, and seems to seat fine on the sensor itself... Do you think that could also be a possible cause? Didn't seem logical but stranger things have happened I guess.... :shrug:

Any help is appreciated...

 

Which sensor did you replace (location on the engine)?

Your CTS may be fine, but a connection could be the problem, including the grounds at the right rear of the intake/head. Measure the resistance of the CTS at a known temperature if you are curious about the sensor itself.

 

Thanks Vader... I have that chart in the shop manual, I'll check it tomorrow..

The sensor I changed is the top one, next to the upper radiator hose on the intake manifold. As far as I knew, the one on the driver side of the head was just for the gauge, which works fine...

 

Yup. You got the right one. Good luck tracking down the wiring.

 

Just figured I'd post an update - wiring looked fine, all grounds in place... So I figured what the heck, and I got ANOTHER new CTS - and bingo, she's fine... the 1st one I bought was defective - happens rarely, but my luck, and I get stuck with the defects all the time LOL...

Thanks Vader, for your help...